Not that I would recommend it over the actual kit but that is how I installed a JJ on that side. I had a piece of .120 wall tube that I cut to length, pressed the JJ body through it and welded it up. While I saved a couple dollars versus the kit, it added more effort to the install.A permanent way to repair the mount is to take your bushing down to an exhaust shop and have them expand a piece of tubing until it is slightly smaller than the large shoulder. Slice that to the correct width to fit snugly inside the mount, press the old bushing in a little bit to locate the sleeve, weld that in. Now you have a lot of press fit area, it won't fail, and you can replace bushings several times before you have to restore the press fit.
I don't like tack welding. If you tack it well enough to stay, you are melting the innards and they really need all the help they can get.